There is a lot of conjecture on this subject and the reason for that is, the time frame in which it takes to show that a substrate is a polluting thing to have in your aquarium!

This usually takes months to years for the first signs to show impacts and by then you have begun to give up or not really noticing that things are going a little pare shaped and except due to costs or you have added more gear to subsidise the drop in water quality or the water changes have increased a lot.

These are my two and i have no substrate in any way in the displays, but I do have four multi level substrates externally!A bare aquarium floor can have life ever spreading out would. https://www.facebook.com/photo.php?